Just like there are no bugs without security impact, is it real to say that this has no impact on flight security? Any error can be a contributing factor.
Safety is ensured by ATC controlers. ETFMS is there to ensure that traffic does not increase beyond controlers capacity. I have read that without ETFMS, the traffic is reduced by 10%. I have been involved in ATC simulations where controlers had to land about 40 flights per hour using new procedures and tools. We have tried with 38 flights per hour, it was too easy for the controlers: their work was perfect even without tools. With 42 flights, controlers were getting angry because the traffic could not be managed. At 40, we could see the benefits of out new procedures and tools (more regular separation of flights). IMHO 10% less traffic gives far enough capacity margin to ensure safety.
